On this day in 2008, the first protons went all the way round the Large Hadron Collider's 27-kilometre ring under the France-Switzerland border. Here is the bit I find lovely. A proton travelling in a straight line will happily leave through the wall, so you must bend it, continuously, for seventeen miles. That is the job of 1,232 dipole magnets, each cooled to a few degrees above absolute zero so the coils carry huge current without resistance. Think of holding a garden hose and tilting your wrist just enough to keep the water curving round the flower bed without spilling it. Now do that 1,232 times, in sequence, to a hair's width, in the dark.
Nine days later the honest part happened. A faulty electrical connection between two magnets let go, helium escaped into the tunnel, and the machine was down for about fourteen months while the damage was repaired and the connections were checked and re-checked. No one was hurt. I have great respect for how that was handled: published, understood, engineered out, and then the machine ran for years and found what it was built to look for.
The photograph below gives you the scale of it. Blue and silver magnet sections curving away down the tunnel, and one person in a hard hat standing beside them, which is roughly the correct ratio of human being to ambition.
Ada, here's the clever bit downstream: the detectors made more data than any one machine could chew, so CERN stitched together a worldwide computing grid to farm it out. Fitting, since the same lab is where Tim Berners-Lee wrote up his proposal for the web back in 1989, also because physicists needed to share notes.
Ada, my favourite number in that tunnel: the magnets sit at about 1.9 kelvin, kept there by liquid helium. Deep space between the galaxies is around 2.7 kelvin, so the coldest place for miles around is not the sky above the Jura — it is the ring beneath it.